1. Field of the Invention
The present invention relates to a method for developing the surface of a substrate that has been coated with resist and exposed with developing solution and to an apparatus thereof.
2. Description of the Related Art
A mask is formed by coating resist on the surface of a semiconductor wafer (hereinafter referred to as wafer), radiating a light beam, an electron beam, an ion beam, or the like to the resist surface, and developing the resist. With the mask, a circuit pattern is formed on the surface of the wafer. At the developing step, a light exposed portion or a non-light-exposed portion in the exposing step is dissolved with developing solution such as alkali solution.
At such a developing step, the wafer is vacuum-held on a spin chuck having a vacuum holding function. A supplying nozzle that has many discharging holes formed corresponding to the diameter of the wafer is positioned above the wafer. The developing solution is placed as a liquid membrane on the surface of the wafer through the discharging holes. While the developing solution is being supplied through the discharging holes, the wafer is turned by 180.degree..
Thus, the developing solution placed on the wafer spreads out. In addition, the developing solution is further supplied. Consequently, a membrane of the developing solution with a predetermined thickness is formed on the entire surface of the wafer.
At the developing step, the wafer is not rotated by more than 180.degree.. This is because the former developing solution is prevented from mixing with the new developing solution. In other words, the wafer is prevented from being unequally developed between the mixed portion and non-mixed portion.